High-accuracy Irradiance Responsivity Calibration Of Solar Backscatter Ultraviolet Spectrometer

Solar Backscatter Ultraviolet Spectrometer (SBUS) is one of the remote sensing instruments in FY-3 meteorological satellite. Its major task is to provide essential data for environmental monitoring, climatic prediction and global climatic change by detecting the vertical distribution of total ozone. In order to achieve the in-flight high-accuracy detection, pre-launch high-accuracy radiometric calibration of the SBUS is crucial. In this thesis, it is firstly reviewed the research work of space-borne remote sensing probes for measurement ozone content at home and abroad, and on the basis of summarizing the radiation calibration systems and methods established during the process of developing the ultraviolet spectral remote sensing instruments in our project group recent years, the potential uncertainties sources in previous irradiance calibration method of the SBUS are proposed. Then, deep analysis and study on every uncertainty source and its effect are made.According to the uncertainty source of atmosphere calibration environment, the methods of theory analysis, numerical simulation and comparison experiment have been adopted. The study results show that the spectral responsivity of the SBUS under atmosphere environment has a relative deviation of about 3.8% to that under vacuum environment in 250-400nm and it is necessary that the whole waveband irradiance calibration of the SBUS is accomplished under vacuum environment.According to the uncertainty source of standard lamps'radiation instability, the lamps'radiation stability testing system is constructed. The study results show that spectral irradiance standard quartz-tungsten-halogen lamp radiates stably, and the MgF2 windowed standard source deuterium lamp has vacuum radiation degradation which is related to the wavelength. A liquid nitrogen cooled screen device is developed to improve deuterium lamp's radiation stability by 7%.According to the uncertainty source of diverging light illumination calibration method, the influence factors of calibration result using parallel light calibration or diverging light calibration have been analyzed. The relative deviation of the calibration results between two calibration methods has been verified by numerical simulation and comparison experiment. The study results show that the relative deviation value is less than any one of the two calibration results'uncertainties and demonstrate the accuracy of the diverging light illumination calibration method.The uncertainty source of "standard lamp irradiance cubic spline interpolation" and "standard lamp irradiance non-uniformity" are eliminated directly. The former improves the interpolation accuracy by about 0.3% using the higher-accuracy SSBUV interpolation formula instead of the cubic spline interpolation; the latter achieves the effective revision towards the incident irradiance value of the spectral irradiance standard quartz-tungsten-halogen lamp and the transfer standard deuterium lamp, the accuracy of lamp irradiance value are improved by about 1% and 3.2% respectively.Finally, on the basis of the study work above, summarize a high-accuracy irradiance responsivity calibration method and accomplish the irradiance calibration of the SBUS. The uncertainty analysis shows that the total irradiance calibration uncertainties of the SBUS in 160-300nm and 250-400nm are±4.3% and±2.8% respectively. Compared with previous calibration methods, the calibration accuracy of the two bands were improved by 4.5% and 1.6%, achieved the purpose of high-accuracy irradiance calibration of the SBUS. The extraterrestrial solar ultraviolet spectrum measured by SBUS is compared with international spectrum average value and an agreement is better than±5%, which demonstrates the accuracy of the high-accuracy irradiance calibration method.